Impact drill



C. FULOP May 19, 1964 IMPACT DRILL 2 Sheets-Sheet 1 Filed Nov. 28, 1962ELE- ":l ,Z f2@ f4@ 47) 550l 60 BIO 4|j INVENTOR. CHA/Les FuLop y 0% C.FULOP IMPACT DRILL May 19, 1964 Filed Nov. 28, 1962 2 Sheets-Sheet 2INVENTOR. C HAELES FuLop m( M a Ik ATTORNEY.

United States Patent 3,133,602 IMPACT BREL Charles Fulop, 131 SkyviewDrive, Seven Hills Village, Ghio Filed Nov. Z8, 1962, Ser. No. 240,505

3 Claims. (Cl. SW3-109) f This invention relates to impact drills andparticularly to a drill having a free floating hammer.

Conducive to a better understanding of the invention, it may be well topoint out that prior art automatic impact drills employ spring biasedhammer elements slidably mounted on a rotating tool holding spindle. Theinter-action between the rapidly rotating spindle and the reciprocatingspring biased hammer quickly creates a great deal of frictional heatwhich limits the proper operation of such devices to relatively shortperiods since the heated parts expand and freeze, or becomeuncomfortably hot to hold unless time out is taken, periodically, topermit the drill to cool.

The primary object of this invention, therefore, is t provide an impactdrill having a reciprocating hammer that floats free and clear ofthespindle, without frictional contact therewith.

Another object is to provide an impact drill whose hainmer is free toreciprocate longitudinally of the spindle and is moved without the useof any biasing spring.

A further object is to provide an impact drill of the type stated,having a free floating massive hammer that is thrown between two spacedcam elements rotating with the spindle. Y

These and other objects of the invention will become apparent from areading of the following speciiication and claims, together with theaccompanying drawing, wherein like parts are referred to and indicatedby like numerals, and wherein: y

FIGURE l is a side elevational view of the impact drill that is thesubject of this invention;

lGURE 2 is a longitudinal sectional view, taken along the line and inthe'd'nection of the arrows 2 2 of FIG- URE 3, showing the free floatinghammer in a first position;

FIGURE 3 is a cross-sectional view of the same, taken along the line andin the dircetion of the arrow 3-3 of FIGURE 2; s

FIGURE 4 is a longitudinal sectional view showing the floating hammer ina second position;

FIGURE 5 is a longitudinal sectional View showing the hammer in a thirdposition;

FIGURE 6 is an exploded view of the device;

FIGURE 7 is a left end view of the hammer taken along the line and inthe direction of the arrows 7-7 of FIG- URE 6;

FIGURE 8 is a right end view of the hammer taken along the line and inthe direction of the arrows 8-8 of FIGURE 6;

FIGURE 9 is a perspective view of the anvil cam disc; and

FIGURE l0 is a perspective ViewY of the hammer throwing disc.

Referring more particularly to the drawing, there is seen in FIGURE lthe impact drill that is the subject of this invention, broadlyindicated'by reference numeral 25B.

Reference numeral 21 indicates the housing of a conventional electricdrill having a threaded motor shaft 23 centered in an end collar 22. v

Reference numeral indicates a hollow cylindrical case having an openrear end, recessed at 42, to fit over the motor housing collar 22.

The case is slotted at 41 to denne a strip to permit the rear end of thecase to be flexed and clamped on to the motor collar 22 by means of aclamping bolt 43.

3,133,602 Patented May 19, 1964 ICC The case 40 has a front wall 44 witha central axial opening 45 therethrough, and 3 sets of spaced andpaired, free turning bearing balls 46 seated in bores 39 in the sidewall thereof, spaced 120 apart, as is seen most clearly in FIGURES 3 and6.

A sleeve 47 lits over the case 40 to keep the bearing balls 46 in place.

A spindle shaft 24 is mounted through a .threaded bore 26 on the end ofthe shaft 23, formingv an extension thereof, as seen in FIGURE 2.

The spindle 214 extends through the housing 40 with its endZ' protrudingthrough the opening 45 thereof. The spindle 24 is supported solely bythe motor shaft 23 and is clear and free of the case 40 and the walls ofthe opening i5 thereof.

Reference numeral Z8 indicates a rst, or hammer throwing disc mounted onthe spindle 24 through a threaded bore 31 which engages external threads33 on the motor end of the spindle. This disc is locked in place by anut 25.

The disc 28 has two diametrically aligned cam teeth 29, and 3i), havinga wide dat top surface 32.

The camming surface of the teeth 29 and 30 are steeply inclined, for apurpose to be hereinafter disclosed.

A second, or anvil disc 35 is :mounted on the threaded end 2.7 of thespindle 24 against shoulder 34, through a central threaded bore 36.

The disc 35 has two diametrically aligned cam teeth 37 and 3S withgradually inclined surfaces, for a purpose to be hereinafter disclosed.

Reference numeral ig indicates alat anvil Vsurface which vsurrounds thecam teeth 37 and 38, as is seen most clearly in FlGURE 9. The two discs23 and 35 are thus spaced apart on the spindle 2d with their respectivecam teeth 29, Btl and 37, 38 faced towardeach other with the high pointof cam teeth 37, 38 positioned slightly ahead, approximately 20, of theprojected plane of the cam teeth 2?, 30 as theyrotate together with thespindle 2.4.

The diameters of the two discs 2S and 35 are such that they clear theinner wall of the case 40 and do nottouch the case as they rotate withthe spindle 24. i

Reference 'numeral 50 indicates a solid, cylindrical hammer lmemberhaving an axial bore 5l therethrough and threelongitudinal semi-circularslots 52, 53 and 54 spaced 120 apart and adapted to receive the bearingballs i6 to mount the hammer within the base 40, for longitu dinalreciprocating movement therein, but secure against rotation. l-

The hammer end face 59 has two diametrically spaced cam follower balls60 and 6l seated therein and free to revolve in their retaining sockets.

The striking end 56 of the hammer 50 has two diametrically spaced,freelyrotating, cam follower balls 57 and 58, and a peripheral collar 55which extends beyond the balls, as is seen rnost clearly in FIGURES 6and 7.

The two cam follower balls 57 and 53 are positioned at to cam followerballs 60 and 61, at opposite end faces S6 and 59 of the hammer 50, ascan be seen in FIGURES 7 and 8.

The hammer 50 is slidably mounted on thecore balls 46, over the spindle24, between the discs 28 and 35, as seen in FIGURES 2 and 3, and is heldagainst'rotation by the balls 45.

The hammer 50 rides solely on the core balls 46 longitudinally of thespindle 24, with its axial bore 51 entirely clear of the spindle 24, asis seen most clearly in FIG- URE 3.

Reference numeral 48 indicates a tool holding chuck that is mounted onthe threaded end 27 of the spindle 24.

In operation rotation of the spindle 24 and the discs 28 and 35 acts tothrow the non-rotating hammer 50 back and forth between the anvil disc35 and the throwing disc 28.

As seen in FIGURES 2, 4 and 5, spindle 24, which has the tool chuck 48mounted on its out end, rotates, in a clock-wise direction, as is commonwith all electric drills.

As the cam teeth 29 and 30 of the throwing disc 2S contact the hammercam follower balls 60 and 61, respectively, the hammer 50 is pushedsharply, by the steeply inclined cam face of the teeth 29 and 30, to theleft until its collar 55 strikes the anvil disc face 49, to take thesecond position illustrated in FIGURE 4.

As the spindle 24 continues to turn the cam returnthrow teeth 37 and 38of the anvil disc 35 ride against the cam follower balls 57 and 58 ofthe hammer 50 and throw it back against the disc 28 with its end face 59positioned against the flat top surface 32 of the cam teeth 29 and 30 ofcam disc 28, as seen in FIGURE 5.

Since the cam teeth 37 and 38 are positioned slightly ahead of theprojected plane of the throwing disc cam teeth 29 and 30, as statedhereinabove, the hammer face 59 will contact the flat tops 32 of the camteeth 29 and 30 just before the cam teeth contact the cam-follower balls60 and 61, as seen in FIGURE 5.

Immediately thereafter, the turning spindle 24 will rotate the cam teeth29 and 30 of disc 28 against the hammer cam-follower balls 60 and 61 tothe position of FIG- URE 2, wherein the throwing and return cycle isrepeated.

Since the cam teeth 29 and 30 of throwing disc 28 are steeply inclined,the hammer 50 will be thrown rapidly against the anvil surface 49 ofdisc 35.

However, since the anvil cam teeth 37 and 38 have gradually rising camsurfaces, the hammer 50 is returned relatively slowly against thethrowing disc 28.

Thus the major hammering impact is delivered during the trip toward theanvil surface 49 from which the impact is transmitted through thespindle end 27 to' a tool held in the chuck 48.

The return movement is relatively slow since its purpose is merely toreturn the hammer to its irst position in readiness for another throw bythe cam teeth 29 and 30 of disc 28.

Since the hammer 50 is relatively long, with a large mass it willdeliver a smart blow against the anvil disc 35.

The to-and-fro movement of the hammer will be sluggish at low speeds,but at spindle rotations of 500 r.p.m. and above, it becomes positiveand vigorous.

It will be noted that there are no large areas of contact betweenstationary and moving surfaces to build up friction and resultant wastedenergy and heat.

The only contact between the hammer 50 and the case 40 is through thefree rolling bearing balls 46.

There is no contact between the hammer and the spindle 24. The spindleand ist supported discs 28 and 35 make no contact with the case 40.

The entire spindle assembly is mounted on the motor shaft 23, and ineffect journaled on the motor bearings.

Thus there are no friction creating sliding surfaces and therefore thedevice can be used for prolonged periods without heating up.

It will now be clear that there has been provided a device whichaccomplishes the objectives heretofore set forth.

While the invention has been disclosed in its preferred form, it is tobe understood that the specific embodiment thereof as described andillustrated herein is not to be considered in a limited sense, as theremay be other forms or modifications of the invention which should alsobe construed to come Within the scope of the appended claims.

I claim:

1. In combination with a portable electric drill having a housing and amotor driven drive shaft centered in a collar on said housing, an impactdrill unit, comprising, a hollow case rigidly mounted at one end on thehousing collar; a tool holding spindle mounted on the end of the driveshaft, forming a continuation thereof, and extending through the case; atool holding chuck mounted on the spindle end, beyond the case; acylindrical hammer slidably journaled on the inner wall of the casehaving cam follower balls embedded in the end faces thereof and an axialbore for clear passage of the spindle therethrough; bearing meansmounted on -the case wall and engaged with longitudinal slots in thehammer to prevent rotation thereof relative to the case and spindle, butleaving the hammer free to reciprocate on the bearing meanslongitudinally of the spindle between spaced and opposed cam discsrigidly mounted on the spindle on opposite sides of the hammer, saiddiscs having sharply inclined cam tracks formed thereon faced toward thehammer end faces and engageable with the cam follower balls thereof, thedistance between the opposed cam discs being such that the hammer endface cam follower balls can contact only one cam disc cam track at atime, the rotation of the spindle and discs acting to rotate thecontacted disc cam track against the cam follower balls of the hammer tothrow the hammer longitudinally of the case and spindle against theother rotating cam disc, whose inclined track, in turn, rides againstthe cam follower balls of the hammer second face, to throw the hammerlongitudinally of the case and spindle, back against the first cam.

2. In combination with a portable electric drill of the type having ahousing and a motor driven drive shaft centered in a collar on saidhousing, an impact drill unit, comprising, a hollow case rigidly mountedat one end on the housing col-lar; three sets of aligned and freelyrotatable bearing balls nested within the case wall and protruding intothe interior of the case, said sets being spaced apart; a spindlemounted on the end of the drive shaft, forming a continuation thereof,and extending through the case without touching it; a tool holding chuckmounted on the spindle end, beyond the case; a cylindrical hammer havingan axial bore therethrough of greater diameter than the spindle, andlongitudinal slots in the peripheral face thereof, spaced 120 apart,mounted in the case, over the spindle, with its peripheral slots engagedby the case bearing balls, whereby the so-supported hammer is free toreciprocate longitudinally of the case and spindle, but restrainedagainst relative rotation thereto; the hammer also having cam followerballs embedded in its end faces; a first, or anvil disc, rigidly mountedon the spindle between the chuck and hammer, having an inclined camtrack faced toward the hammer; a second, or throwing, disc rigidlymounted on the spindle on the far side of the hammer, having an inclinedcam track faced toward the hammer; the distance between the opposed camdiscs being such that the hammer end face cam follower balls can contactonly one disc cam track at a time; the rotation of the spindle and discsacting to move the contacted disc cam track against the cam followerballs of the hammer to throw the hammer longitudinally of the case andspindle against the other rotating cam disc, whose inclined track, inturn rides against the cam follower balls of the hammer second face, tothrow the hammer longitudinally of the case and spindle, back againstthe first cam, or anvil disc.

3. In combination with a portable electrical drill of the type having ahousing and a motor driven drive shaft centered in a collar on saidhousing, an impact drill unit, comprising, a hollow case rigidly mountedat one end on the housing collar; three sets of aligned and freelyrotatable bearing balls nested within the case wall and protruding intothe interior of the case, said sets being spaced 120 apart; a spindlemounted on the end of the drive shaft, forming a continuation thereof,and extending through the case without touching it; a tool holding chuckmounted on the spindle end, beyond the case; a cylindrical hammer havingan axial bore therethrough of greater diameter than the spindle, andlongitudinal slots in the peripheral face thereof, spaced 120 apart,mounted in the case, over the spindle, with its peripheral slots engagedby the case bearing balls, whereby the sosupported hammer is free toreciprocate longitudinally of the case and spindle, but restrainedagainst relative rotation thereto; the hammer also having cam followerballs embedded in both its end faces, the embedded balls of one end facebeing radially displaced approximately 90 with reference to those of theother end face; a rst, or anvil, disc mounted rigidly on the spindlebetween the chuck and hammer, having a gradually inclined cam trackfaced toward the hammer; a second, or throwing, disc rigidly mounted onthe spindle on the far side of the hammer, having a steeply inclined camtrack faced toward the hammer, the relative positions of the so opposedcam tracks being such that as the spindle rotates the high point of thethrowing disc cam track is ahead of the low point of the anvil disc, orreturn, cam

track; the distance between the opposed cam disc tracks being such thatthe hammer end face cam follower balls can contact only one disc camtrack at a time; the rotation of the spindle and discs acting to movethe contacted disc track against the cam follower balls of the hammer tothrow the hammer longitudinally of the spindle against the otherrotating cam disc, whose inclined track, in turn, rides against the camfollower balls of the second hammer face, to throw the hammer longi- 10tudinally of the spindle, back against the rst disc.

References Cited in the file of this patent UNITED STATES PATENTSSnodgrass July 1l, 1944 2,968,960 Fulop Ian. 24, 1961

1. IN COMBINATION WITH A PORTABLE ELECTRIC DRILL HAVING A HOUSING AND AMOTOR DRIVEN DRIVE SHAFT CENTERED IN A COLLAR ON SAID HOUSING, AN IMPACTDRILL UNIT, COMPRISING, A HOLLOW CASE RIGIDLY MOUNTED AT ONE END ON THEHOUSING COLLAR; A TOOL HOLDING SPINDLE MOUNTED ON THE END OF THE DRIVESHAFT, FORMING A CONTINUATION THEREOF, AND EXTENDING THROUGH THE CASE; ATOOL HOLDING CHUCK MOUNTED ON THE SPINDLE END, BEYOND THE CASE; ACYLINDRICAL HAMMER SLIDABLY JOURNALED ON THE INNER WALL OF THE CASEHAVING CAM FOLLOWER BALLS EMBEDDED IN THE END FACES THEREOF AND AN AXIALBORE FOR CLEAR PASSAGE OF THE SPINDLE THERETHROUGH; BEARING MEANSMOUNTED ON THE CASE WALL AND ENGAGED WITH LONGITUDINAL SLOTS IN THEHAMMER TO PREVENT ROTATION THEREOF RELATIVE TO THE CASE AND SPINDLE, BUTLEAVING THE HAMMER FREE TO RECIPROCATE ON THE BEARING MEANSLONGITUDINALLY OF THE SPINDLE BETWEEN SPACED AND OPPOSED CAM DISCSRIGIDLY MOUNTED ON THE SPINDLE ON OPPOSITE SIDES OF THE HAMMER, SAIDDISCS HAVING SHARPLY INCLINED CAM TRACKS FORMED THEREON FACED TOWARD THEHAMMER END FACES AND ENGAGEABLE WITH THE CAM FOLLOWER BALLS THEREOF, THEDISTANCE BETWEEN THE OPPOSED CAM DISCS BEING SUCH THAT THE HAMMER ENDFACE CAM FOLLOWER BALLS CAN CONTACT ONLY ONE CAM DISC CAM TRACK AT ATIME, THE ROTATION OF THE SPINDLE AND DISCS ACTING TO ROTATE THECONTACTED DISC CAM TRACK AGAINST THE CAM FOLLOWER BALLS OF THE HAMMER TOTHROW THE HAMMER LONGITUDINALLY OF THE CASE AND SPINDLE AGAINST THEOTHER ROTATING CAM DISC, WHOSE INCLINED TRACK, IN TURN, RIDES AGAINSTTHE CAM FOLLOWER BALLS OF THE HAMMER SECOND FACE, TO THROW THE HAMMERLONGITUDINALLY OF THE CASE AND SPINDLE, BACK AGAINST THE FIRST CAM.